1. Field of the Invention
This invention relates to an apparatus for connecting digital data, and more particularly, to an apparatus for connecting digital data recorded on magnetic tape which has been splice edited.
2. Description of the Prior Art
The applicant has earlier proposed a method of transmitting a pulse coded modulation (PCM) signal with error correction capabilities. Such a method is disclosed in, for example, British specification No. 2060227A, corresponding to U.S. patent application Ser. No. 195,625, filed Oct. 9, 1980, now U.S. Pat. No. 4,393,502. In accordance with the above disclosure, a one-channel PCM signal is divided into two series of words: even numbered words and odd numbered words. An even/odd distributor is used in a digital encoder to divide the one-channel PCM signal into the two word series. The even numbered words are delayed by an amount D through a delay circuit. The delayed even numbered word series and the odd numbered word series (which are not delayed) are supplied to separate correction encoders where the words are encoded. After the encoding step, the words are synthesized and modulated by a modulator for transmission.
The above-described method of transmitting a PCM signal can be used, for example, in a digital tape recorder in which an audio signal is digitally recorded on a magnetic tape. It is sometimes desirable, however, to splice edit a magnetic tape containing a digital signal recorded as described above. In a splice editing operation, the even numbered word series and odd numbered word series are supplied to error correction circuits where, in addition to error correction operations, appropriate compensation is applied to correct for the delay in the even numbered word series. After the error correction operations, a cross-fader is used to connect the data recorded on the magnetic tape before and after the splice editing point.
An interval with many errors in the data can occur before and after a splice editing point on the magnetic tape. A muting operation is usually applied to the interval where the errors are detected in order to improve the signal reproduced from the cross-faded data. If the time for the beginning of the cross-fading operation is fixed in relation to the position of the splice editing point, and if the muting interval is long, the average level of the PCM signal reproduced in the cross-fade interval can be reduced to an unsatisfactory level due to the operation of the cross-fader.